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Ítem Comparison of TiO2 targets manufactured by APS and sintering processes for PAPVD coatings suitable in technological and medical applications(ASM International, 2018-01-01) Jaramillo Raquejo D.; Palacio C.C.; Ageorges H.; Jaramillo Raquejo D.; Palacio C.C.; Ageorges H.; Universidad EAFIT. Departamento de Ciencias; Electromagnetismo Aplicado (Gema)In surface science of functional oxides, Titanium dioxide (TiO2) is one of the most investigated crystalline systems either in rutile or anatase phases. Rutile phase is widely used in microelectronic, tribological applications and in the conversion of solar energy. Anatase phase is used in self-cleaning, antifogging, photo-catalytic and biomedical technologies. This work focuses on studying the required process conditions to obtain TiO2 targets by APS onto metallic substrates using commercial TiO2 powders (Oerlikon Metco in Switzerland) with suitable physical and chemical properties for technological and medical applications as PAPVD coatings. APS targets were compared to sintered ones. The raw powders were characterized by laser diffraction, SEM, XRF and XRD while the characteristics of the APS-deposited targets as well as the sintered ones were determined by SEM and XRD to identify the constituent phases. This work allowed confirming the advantages and limitations of both processes in terms of grain size, chemical composition, microstructural homogeneity and density in order to choose the best option to manufacture targets for PAPVD coatings for technological and medical applications. © 2018 ASM International® All rights reserved.Ítem Growth of magnetite films by a hydrogel method(Elsevier B.V., 2017-06-15) Velásquez, A.A.; Marín, C.C.; Urquijo, J.P.; Universidad EAFIT. Departamento de Ciencias Básicas; Electromagnetismo Aplicado (Gema)Magnetite (Fe3O4) films were grown on glass substrates by formation and condensation of complex of iron oxides in an agarose hydrogel. The obtained films were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Room Temperature Mössbauer Spectroscopy (TMS), Vibrating Sample Magnetometry (VSM), Atomic Force Microscopy (AFM) and Voltage vs. Current measurements by the four-point method. FTIR and TGA measurements showed that some polymer chains of agarose remain linked to the surface of the magnetic particles of the films after heat treatment. SEM measurements showed that the films are composed by quasi spherical particles with sizes around 55 nm. Mössbauer spectroscopy measurements showed two sextets with broaden lines, which were assigned to magnetite with a distributed particle size, and two doublets, which were assigned to superparamagnetic phases of magnetite. For the specific dimensions of the films prepared, measurements of Voltage vs. Current showed an ohmic behavior for currents between 0 and 200 nA, with a resistance of 355 kO. © 2017 Elsevier B.V.Ítem Optimización de sustrato para germinación de semilla de lechuga crespa en cultivos hidropónicos(Universidad EAFIT, 2018) Echeverry Buitrago, Luisa Fernanda; Acosta Maya, Diego AndrésÍtem Prediction of a flying droplet landing over a non-flat substrates for ink-jet applications(Springer-Verlag France, 2019-01-01) Arango I.; Bonil L.; Posada D.; Arcila J.; Arango I.; Bonil L.; Posada D.; Arcila J.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecatrónica y Diseño de MáquinasPrinting with inkjet technology has found new forms of application in the industry and in this article we study this technology focused on printing on non-flat surfaces. Since there is no print history over distances greater than 1 mm due to the rupture phenomenon, an initial quality standard is defined to measure achievements in a relative manner. An interactive method is used that requires the user to approach the machine in multiple analyzes of different types. The first approach is a mathematical model this model was constructed to predict the drop distance of the drop in the non-planar substrate with respect to the planned one in the flat substrate, taking into account that most of the drops fall to different heights presenting a greater or lesser state of development the phenomena present in the flight. The results allow to initiate a process of compensation that avoids the distortion of the figure to improve the printing resolution. The results are validated using a relative quality through industrial ink-jet printer with heads capable of injecting functional fluids. The initial result indicates that in standard surface printing with print relative quality already defined, it can be used only for low resolution formats with thick lines, and the result can be improved when the original figure is treated by compensating the distance between the numerical prediction and the initial objective. © 2019, Springer-Verlag France SAS, part of Springer Nature.Ítem Synthesis of Alumina Thin Films Using Reactive Magnetron Sputtering Method(IOP PUBLISHING LTD, 2017-06-13) Angarita G.; Palacio C.; Trujillo M.; Arroyave M.; Angarita G.; Palacio C.; Trujillo M.; Arroyave M.; Universidad EAFIT. Departamento de Ciencias; Electromagnetismo Aplicado (Gema)Alumina (Al2O3) thin films were deposited on Si (100) by Magnetron Sputtering in reactive conditions between an aluminium target and oxygen 99.99% pure. The plasma was formed employing Argon with an R.F power of 100 W, the dwelling time was 3 hours. 4 samples were produced with temperatures between 350 and 400 °C in the substrate by using an oxygen flow of 2 and 8 sccm, the remaining parameters of the process were fixed. The coatings and substrates were characterized using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) in order to compare their properties before and after deposition. The films thicknesses were between 47 and 70 nm. The results show that at high oxygen flow the alumina structure prevails in the coatings while at lower oxygen flow only aluminum is deposited in the coatings. It was shown that the temperature increases grain size and roughness while decreasing the thicknesses of the coatings. © Published under licence by IOP Publishing Ltd.